Comparison of Weight-Based Dosing Strategies for Intravenous Immunoglobulin in Patients with Hematologic Malignancies

Study objective: Intravenous immunoglobulin (IVIG) is a weight-based therapy used to treat and prevent infections in patients with hematologic malignancies. IVIG doses were calculated traditionally using actual body weight (ABW). However, limited pharmacokinetic data suggest dosing strategies using ideal body weight (IBW) or adjusted body weight (adjBW) may be appropriate given the small volume of distribution of IVIG. Our objective was to compare the effectiveness of using a precision-dosing strategy (IBW or adjBW) with a traditional-dosing strategy (ABW) for IVIG in patients with hematologic malignancies or those undergoing hematopoietic stem cell transplant, as well as to perform an IVIG drug use analysis.

Design: Retrospective cohort study.

Setting: Academic medical center.

Patients: Between April 2014 and September 2016, 209 IVIG encounters met inclusion criteria for the primary outcome. Of those encounters, 125 were dosed using the traditional-dosing strategy, and 84 used the precision-dosing strategy.

Measurements and main results: The primary outcome was infection rate within 30 days of IVIG administration. Secondary outcomes included 60-day infection rate, immunoglobulin G (IgG)-level response (IgG higher than 400 mg/dl), and realized and potential IVIG savings. No difference in 30-day infection rate between precision- and traditional-dosing strategies was identified (15.5% vs 16%, respectively, p=0.823). Similarly, no difference was identified in the 60-day infection rate between groups (23.2% vs 19.8%, respectively, p=0.568). Levels of IgG obtained after IVIG repletion showed a treatment response rate of 86% in both groups. Use of a precision-dosing strategy achieved $2600/month in institutional savings with the opportunity for an additional $4600/month in savings with complete adherence to this dosing strategy.

Conclusion: No differences in infection rate and IgG-level response were identified when a precision-dosing strategy was used. Implementation of an IVIG precision-dosing strategy provided institutional cost savings.